CHAPTER VIII. INSTINCT.

Natural instincts are lost under domestication: a remarkable instance of
this is seen in those breeds of fowls which very rarely or never become
"broody," that is, never wish to sit on their eggs. Familiarity alone
prevents our seeing how largely and how permanently the minds of our
domestic animals have been modified. It is scarcely possible to doubt that
the love of man has become instinctive in the dog. All wolves, foxes,
jackals and species of the cat genus, when kept tame, are most eager to
attack poultry, sheep and pigs; and this tendency has been found incurable
in dogs which have been brought home as puppies from countries such as
Tierra del Fuego and Australia, where the savages do not keep these
domestic animals. How rarely, on the other hand, do our civilised dogs,
even when quite young, require to be taught not to attack poultry, sheep,
and pigs! No doubt they occasionally do make an attack, and are then
beaten; and if not cured, they are destroyed; so that habit and some degree
of selection have probably concurred in civilising by inheritance our dogs.
On the other hand, young chickens have lost wholly by habit, that fear of
the dog and cat which no doubt was originally instinctive in them, for I am
informed by Captain Hutton that the young chickens of the parent stock, the
Gallus bankiva, when reared in India under a hen, are at first excessively
wild. So it is with young pheasants reared in England under a hen. It is
not that chickens have lost all fear, but fear only of dogs and cats, for
if the hen gives the danger chuckle they will run (more especially young
turkeys) from under her and conceal themselves in the surrounding grass or
thickets; and this is evidently done for the instinctive purpose of
allowing, as we see in wild ground-birds, their mother to fly away. But
this instinct retained by our chickens has become useless under
domestication, for the mother-hen has almost lost by disuse the power of
flight.

Hence, we may conclude that under domestication instincts have been
acquired and natural instincts have been lost, partly by habit and partly
by man selecting and accumulating, during successive generations, peculiar
mental habits and actions, which at first appeared from what we must in our
ignorance call an accident. In some cases compulsory habit alone has
sufficed to produce inherited mental changes; in other cases compulsory
habit has done nothing, and all has been the result of selection, pursued
both methodically and unconsciously; but in most cases habit and selection
have probably concurred.